#include <linux/blkdev.h>
#include <linux/gfp.h>
#include <linux/blk-mq.h>
-#include <linux/lockdep.h>
#include "blk.h"
#include "blk-mq.h"
static void blk_account_io_flush(struct request *rq)
{
- struct hd_struct *part = &rq->rq_disk->part0;
+ struct block_device *part = rq->rq_disk->part0;
part_stat_lock();
part_stat_inc(part, ios[STAT_FLUSH]);
INIT_LIST_HEAD(&fq->flush_queue[1]);
INIT_LIST_HEAD(&fq->flush_data_in_flight);
- lockdep_register_key(&fq->key);
- lockdep_set_class(&fq->mq_flush_lock, &fq->key);
-
return fq;
fail_rq:
if (!fq)
return;
- lockdep_unregister_key(&fq->key);
kfree(fq->flush_rq);
kfree(fq);
}
+
+/*
+ * Allow driver to set its own lock class to fq->mq_flush_lock for
+ * avoiding lockdep complaint.
+ *
+ * flush_end_io() may be called recursively from some driver, such as
+ * nvme-loop, so lockdep may complain 'possible recursive locking' because
+ * all 'struct blk_flush_queue' instance share same mq_flush_lock lock class
+ * key. We need to assign different lock class for these driver's
+ * fq->mq_flush_lock for avoiding the lockdep warning.
+ *
+ * Use dynamically allocated lock class key for each 'blk_flush_queue'
+ * instance is over-kill, and more worse it introduces horrible boot delay
+ * issue because synchronize_rcu() is implied in lockdep_unregister_key which
+ * is called for each hctx release. SCSI probing may synchronously create and
+ * destroy lots of MQ request_queues for non-existent devices, and some robot
+ * test kernel always enable lockdep option. It is observed that more than half
+ * an hour is taken during SCSI MQ probe with per-fq lock class.
+ */
+void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
+ struct lock_class_key *key)
+{
+ lockdep_set_class(&hctx->fq->mq_flush_lock, key);
+}
+EXPORT_SYMBOL_GPL(blk_mq_hctx_set_fq_lock_class);